Content originally posted in LPCWare by ArriaLive on Fri Dec 19 12:58:06 MST 2014
I see that I did not get any replies, even from NXP.
I tried a different approach with this, taking the BASE_AUDIO_CLK signal through an SGPIO (rate verified), then through the GIMA to the state-controlled timer (SCT). I have verified that some signal is getting through to the SCT, and when I change the BASE_AUDIO_CLK frequency, the SCT changes as well, so I know they're connected. However, I cannot make heads or tails out of the frequency coming into the SCT. It simply isn't right. It clocks at about 3.48x the expected rate. Not 4x, which might be a configuration problem, 3.48x. Where does that come from? I divided the signal by 4 just to see if that would work, but of course it remained off by about the same percentage.
Given this experiment, and the one above, and given that no one else seems to know anything about the GIMA, or even use it, I have to assume that the GIMA simply doesn't work. In each case, I'm getting values that are 6-10% off what is expected. If I'm missing something, someone tell me, but after several days experimenting each path, the results appear to point to errors in the GIMA.
NXP, or anyone else, can you provide a demonstration--using the audio clock as an input--that proves my conclusion wrong?